Block usage of return() in magrittr pipelines

return() inside a magrittr pipeline does not actually execute return() like you'd expect:

Usage

pipe_return_linter()

Details

bad_usage <- function(x) {
  x %>%
    return()
  FALSE
}

bad_usage(TRUE) will return FALSE! It will technically work "as expected" if this is the final statement in the function body, but such usage is misleading. Instead, assign the pipe outcome to a variable and return that.

See also

linters for a complete list of linters available in lintr.

Tags

best_practices, common_mistakes

Examples

# will produce lints
lint(
  text = "function(x) x %>% return()",
  linters = pipe_return_linter()
)
#> <text>:1:19: warning: [pipe_return_linter] Avoid return() as the final step of a magrittr pipeline.  Instead, assign the output of the pipeline to a well-named object and return that.
#> function(x) x %>% return()
#>                   ^~~~~~~~

# okay
code <- "function(x) {\n  y <- sum(x)\n  return(y)\n}"
writeLines(code)
#> function(x) {
#>   y <- sum(x)
#>   return(y)
#> }
lint(
  text = code,
  linters = pipe_return_linter()
)
#> ℹ No lints found.